my zf-5 is brutal on the highway as far as mpg goes. is there any way to swap in a zf-6? would this be worth the cost/aggrevation of the new/salvaged tranny?

 

It would would definitely not be worth it. The ZF-6 has an extra middle gear, the O/D ratio's are almost identical.

You'd be better off with a taller gearset or an oftermarket O/D unit.

 

its a TON of work. theres floor board mods that have to be made, the tranny mount has to be moved back, if you have 4x4 you will need the tcase from a SD then the driveshaft changes, the flanges on the shafts need to be changed also.

i really wanted to go to the zf-6 cause it closes up that gap alot between 2-3 but i couldnt find a tranny for less than $2750 for a reman including the core charge and the tcase is another $1200 including core then clutch, hydraulics, engine plate, shorter dowel pins, the swap was getting over $5k by the time i buy everything and have the driveshafts done. and not including all my labor.....i had a buddy that did it, but he had a wrecked SD donor truck, he took the easy way out and put a 2" body lift on it instead of workin over the floor board.

for all that money i can get a us gear overdrive and get a rebuilt 5 speed for alot less money and agrivation then i got a 10 speed and 20% overdrive with the tranny in 4th 1:1 would make the 4.10 a 3.28.

i belive both trannys have .84 OD which would make the 4.10, 3.44 add the extra od in that another .80 or 20% off would be a 2.75

at 65 in od right now im about 2700rpms 20% off that would be about 2100 rpms i would imagine picking up a couple mpg running down the hwy.


it would be great to have theese OD gears going down the highway, im looking at getting mine this summer, waitin for the clutch in the truck to get a little more worn.

shifting the OD unit takes some getting used to. if you can shift your truck with out the clutch you will easily be able to shift the splitter. its identical to driving a truck with a 2 speed rear end. just gotta be able to float the gears to let it shift.

 

dad's got a peterbilt w/ an 18spd, sure he could teach me. thank you both very much for the info. the 10spd unit youre talking about, bareback, what would it cost and how tough would it be to install?

 

its from us gear http://usgear.com/dual_range.htm

its $2595 plus the install kit which i think its about $200 then you will need the back driveshaft shortened and the front lenthened which a local shop told me $400 including new ujoints and slip yolk.

it actually uses your 5 speed then its a 2 speed unit that goes between the trans and tcase that you can drive it just like your 5 and shift the unit when your not moving, but all the times ive towed with my buddies truck ive used the overdrive and normal to make the gears closer togethor. usually when were drivin empty we just leave it in OD

ive got a buddy that has one at it was an easy install. pulled the tcase out it bolted right up then the wiring and driveshafts. when we did his truck we put the front driveshaft in and crawled to the driveshaft shop. it took us about 4 hours start to getting to the driveshaft shop